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. 2022 Nov 12;14(11):2508.
doi: 10.3390/v14112508.

Epidemiological and Clinical Features of SARS-CoV-2 Variants Circulating between April-December 2021 in Italy

Alessia Lai  1 , Annalisa Bergna  1 , Carla Della Ventura  1 , Stefano Menzo  2 , Bianca Bruzzone  3 , Fabio Sagradi  4 , Francesca Ceccherini-Silberstein  5 , Alessandro Weisz  6 , Nicola Clementi  7 , Gaetano Brindicci  8 , Ilaria Vicenti  9 , Lolita Sasset  10 , Sara Caucci  2 , Benedetta Corvaro  2 , Silvia Ippoliti  2 , Carla Acciarri  2 , Vanessa De Pace  3 , Leonardo Lanfranchi  4 , Maria C Bellocchi  5 , Giorgio Giurato  6 , Roberto Ferrarese  7 , Antonella Lagioia  8 , Daniela Francisci  11 , Martina L Colombo  1 , Samuel Lazzarin  1 , Matilde Ogliastro  12 , Maria R Cappelletti  4 , Marco Iannetta  13 , Francesca Rizzo  6 , Carlo Torti  14 , Maurizio Fumi  15 , Morena d'Avenia  16 , Stefano Brusa  17 , Francesca Greco  18 , Angela Menchise  19 , Vittoria Letizia  20 , Emilia Vaccaro  21 , Carmen R Santoro  8 , Chiara Fraccalvieri  3 , Sophie Testa  4 , Luca Carioti  5 , Teresa Rocco  6 , Annalisa Saracino  8 , Annamaria Cattelan  10 , Massimo Clementi  7 , Loredana Sarmati  13 , Agostino Riva  1 , Massimo Galli  1 , Spinello Antinori  1 , Gianguglielmo Zehender  1 , Sars-CoV-Italian Research Enterprise-Scire Collaborative Group  2
Affiliations

Epidemiological and Clinical Features of SARS-CoV-2 Variants Circulating between April-December 2021 in Italy

Alessia Lai et al. Viruses. .

Abstract

SARS-CoV-2 is constantly evolving, leading to new variants. We analysed data from 4400 SARS-CoV-2-positive samples in order to pursue epidemiological variant surveillance and to evaluate their impact on public health in Italy in the period of April-December 2021. The main circulating strain (76.2%) was the Delta variant, followed by the Alpha (13.3%), the Omicron (5.3%), and the Gamma variants (2.9%). The B.1.1 lineages, Eta, Beta, Iota, Mu, and Kappa variants, represented around 1% of cases. There were 48.2% of subjects who had not been vaccinated, and they had a lower median age compared to the vaccinated subjects (47 vs. 61 years). An increasing number of infections in the vaccinated subjects were observed over time, with the highest proportion in November (85.2%). The variants correlated with clinical status; the largest proportion of symptomatic patients (59.6%) was observed with the Delta variant, while subjects harbouring the Gamma variant showed the highest proportion of asymptomatic infection (21.6%), albeit also deaths (5.4%). The Omicron variant was only found in the vaccinated subjects, of which 47% had been hospitalised. The diffusivity and pathogenicity associated with the different SARS-CoV-2 variants are likely to have relevant public health implications, both at the national and international levels. Our study provides data on the rapid changes in the epidemiological landscape of the SARS-CoV-2 variants in Italy.

Keywords: Italy; SARS-CoV-2; epidemiology; variants circulation.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Dynamics of the SARS-CoV-2 epidemic in Italy. (a) Variant prevalence in terms of clades; (b) variant prevalence in terms of lineages.
Figure 2
Figure 2
Spatial distribution of lineages in different regions.
Figure 3
Figure 3
Proportion of unvaccinated and vaccinated subjects over time.
Figure 4
Figure 4
Clinical status/outcome in (a) subjects vaccinated with one dose, (b) subjects vaccinated with two or three doses, and (c) unvaccinated subjects during the study period.
Figure 5
Figure 5
Proportion of clinical status in the vaccinated and unvaccinated subjects infected with the different variants.
See this image and copyright information in PMC

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